System and method for producing battery cell electrodes

Abstract

The invention relates to a system (100) for producing battery cell electrodes, comprising: a first roller arrangement (110) which is set up to calender an electrode web (EB); a heating arrangement (120) which is set up to heat the electrode web (EB) after the calendering; and a second roller arrangement (130) which has at least one second roller (132), wherein the at least one second roller (132) comprises at least one first roller region having a first roller diameter (D1) and at least one second roller region having a second roller diameter (D2), the second roller diameter (D2) being greater than the first roller diameter (D1), and wherein the at least one first roller region corresponds to a first web region (B1) of the electrode web (EB) and the at least one second roller region corresponds to a second web region (B2) of the electrode web (EB), the first web region (B1) and the second web region (B2) having different coatings and / or a different material composition.

Description

[0001] 24-1475

[0002] Manufacturing system and manufacturing process for battery cell electrodes

[0003] The present disclosure relates to a manufacturing system for battery cell electrodes and a manufacturing process for battery cell electrodes. In particular, the present disclosure relates to the homogenization of anode properties, such as camber and thickness, in battery cell production.

[0004] State of the art

[0005] The production of anodes for battery cells, especially for lithium-ion batteries, involves several process steps aimed at optimizing the electrochemical performance and lifespan of the cells. Exemplary process steps include applying an anode slurry, consisting of an active material, binders, and solvents, to a copper foil. This is followed by drying the coated foil, calendering to homogenize the layer thickness and density, and cutting the anode to the desired size. Subsequently, vacuum drying or, alternatively, jelly roll drying (JR drying) is performed, in which the anodes are dried in a coiled state.

[0006] During the drying process and / or storage of the anodes, especially in the wound coil state, a stress build-up can occur in the electrode, negatively affecting its properties. Undesirable effects include a local increase in camber, resulting in an uneven camber profile, the appearance of electrode waviness, and an increase in thickness, leading to an uneven thickness profile. Furthermore, the stress build-up reduces the anode's deformability, which is necessary during subsequent cell operation to prevent damage to the battery cell. For example, reduced anode deformability increases the risk of foil rupture during charging and discharging processes and can impair the battery cell's lifespan and safety. 24-1475

[0007] Disclosure of the invention

[0008] The object of this disclosure is to specify a manufacturing system and a manufacturing process for battery cell electrodes that can improve the quality of the electrodes. In particular, it is an object of this disclosure to increase the reliability and service life of the battery cells.

[0009] This problem is solved by the subject matter of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0010] According to an independent aspect of the present disclosure, a manufacturing system for electrodes of battery cells, such as lithium-ion cells, is specified.The manufacturing system comprises: a first roller arrangement configured to calender an electrode web; a heating arrangement configured to heat the electrode web after calendering; and a second roller arrangement with at least one second roller, wherein the at least one second roller comprises at least one first roller section with a first roller diameter and at least one second roller section with a second roller diameter, wherein the second roller diameter is larger than the first roller diameter, and wherein the at least one first roller section corresponds to a first web section of the electrode web and the at least one second roller section corresponds to a second web section of the electrode web, wherein the first web section and the second web section have different coatings and / or different material properties.

[0011] According to the invention, after calendering, the electrode web undergoes a heating process to selectively generate a springback, i.e., a renewed increase in the thickness of the electrode web, to 24-1475 mm. This is followed by a further process step in which specific areas of the electrode web are elongated by a roller with a locally increased diameter. For example, force can be applied to an area with an uncoated conductive foil, causing this area to undergo plastic elongation. This allows, in particular, the compensation of a length difference between coated and uncoated areas. The combination of both measures, i.e., heating and local elongation, leads to a reduction in camber and a reduction in stress build-up. This results in improved electrode quality as well as increased reliability and extended service life of the battery cells.

[0012] In the context of battery cell manufacturing, particularly for anodes and cathodes, the term "camber" refers to a bending or curvature of a flat, thin layer of material, such as an electrode. This curvature often occurs unintentionally during processing and can be caused by mechanical or thermal stresses that build up in the material during the manufacturing process, for example, during calendering, drying, or storage.

[0013] The electrode of the present disclosure is a conductive component that serves either as an anode (positive electrode) or as a cathode (negative electrode). Such an electrode typically consists of an active material applied to a support material or substrate by means of a coating process. The substrate is, for example, a metallic foil, such as copper for the anode or aluminum for the cathode. This substrate serves as a support for the active material, which is applied by means of the coating process. In this process, a mixture of active materials (such as graphite for the anode or lithium metal oxides for the cathode), binders, and conductive additives is uniformly applied to the substrate.

[0014] Preferably, the electrode is an anode.

[0015] The term "electrode track" refers to a continuous, flat layer of electrode material (anode or cathode) that is produced during the manufacturing process of 24-1475

[0016] Battery cells are processed in the form of a ribbon. This ribbon typically consists of a thin metal layer (e.g., copper for the anode and aluminum for the cathode) as a substrate material, onto which a layer of the active material (such as graphite for the anode or lithium metal oxide for the cathode) is applied.

[0017] The first roller assembly is set up to calender the electrode web. Calendering is a process in which a material is passed through rollers to control its thickness and surface area. In the context of battery cell manufacturing, particularly in the production of anodes and cathodes, calendering is used to achieve a uniform electrode thickness and density.

[0018] Preferably, the first roller arrangement comprises two first rollers or a pair of rollers arranged on opposite sides to calender the electrode web between them.

[0019] Preferably, the manufacturing system further comprises a web tension adjustment mechanism configured to adjust the web tension of the electrode web at (e.g., before and / or after) the second roller assembly. The term "web tension" refers to the tension or tensile force exerted on the continuously moving electrode web as it passes through the manufacturing system. Precise adjustment of the web tension can further assist in compensating for length differences between the various web sections via the second roller assembly.

[0020] Preferably, the web tension adjustment mechanism is designed to adjust the web tension of the electrode web at (e.g. in front of and / or behind) the second roller arrangement in a range between 0.1 and 1.5 N / mm web width (Newtons per millimeter of web width), in particular in a range between 0.3 and 0.9 N / mm web width.

[0021] The heating arrangement is designed to warm the electrode web after calendering. Heating the electrode web after calendering intentionally induces a springback, i.e., a rebound in the thickness of the electrode web. For example, over-pressing can occur during calendering, and the heating of the electrode web can then be performed such that the electrode web has a target thickness after heating. Triggering the springback immediately after calendering reduces camber and stress buildup.

[0022] Preferably, the electrode path during heating is a free electrode path. A free electrode path after calendering refers to the section of the electrode path located immediately after calendering and not supported by rollers or other machine parts. This part of the electrode path "hangs" freely between the process steps, in particular between calendering by the first roller arrangement and elongation by the second roller arrangement.

[0023] Preferably, the heating arrangement comprises at least one first heating device and at least one second heating device arranged on opposite sides of the electrode track. This allows, for example, the double-sided coated electrode track to be heated uniformly from both sides.

[0024] Preferably, the heating arrangement comprises at least one infrared heating device. The at least one infrared heating device can, for example, be configured to heat the electrode path with an infrared wavelength in a range between 1 pm and 5 pm.

[0025] Preferably, the heating arrangement comprises at least one induction heating device.

[0026] Preferably, the heating arrangement includes at least one gas heating device.

[0027] Preferably, the heating arrangement is configured to heat a surface of the electrode track to a temperature of 80°C or more. For example, the heating arrangement can be configured to heat the surface of the electrode track to a temperature in the range between 100°C and 150°C. 24-1475

[0028] Preferably, the heating arrangement is configured to heat the electrode track for a heating duration of 0.5 s or more. For example, the heating arrangement can be configured to heat the electrode track for a heating duration of approximately 1 s.

[0029] The second roller arrangement is configured to selectively or locally lengthen the electrode web to reduce the camber effect. This is achieved by at least one second roller with axially different diameters. In particular, the at least one first roller section with the first roller diameter corresponds to a first web section of the electrode web, and the at least one second roller section with the larger second roller diameter corresponds to a second web section of the electrode web.

[0030] Preferably, the second roller arrangement is configured to process the electrode web after heating by the heating arrangement. However, the present disclosure is not limited to this, and the processing of the electrode web by the second roller arrangement can alternatively also take place before heating or even before calendering.

[0031] Preferably, at least one second roller is a guide roller. Guide rollers (also called "guide rollers") serve to precisely guide, support, and control the movement of the flexible electrode web in the desired direction, i.e., the web direction, to ensure uniform processing. The term "web direction" refers to the direction of movement of the electrode web as it is guided through a manufacturing system, such as a roll-to-roll system.

[0032] The first and second web sections have different coatings and / or material properties, with different forces exerted on them due to the different roller diameters. This allows for the compensation of length differences between the web sections, e.g., in the 24-1475 direction. This length compensation leads to a reduction in camber and a reduction in stress build-up.

[0033] Preferably, the first path region of the electrode path corresponds to a region with an electrode coating.

[0034] Preferably, the second path area of ​​the electrode path corresponds to an area without electrode coating.

[0035] Preferably, the second region of the electrode path corresponds to a region with a current collector. A current collector on the electrode path refers to a central and / or peripheral region of the electrode coating that is not coated with active material. In battery manufacturing, particularly in lithium-ion batteries, the current collector can denote the uncoated part of the electrode (anode or cathode) that is intended to safely conduct the electric current from the electrode to the battery contacts or terminals.

[0036] Preferably, the at least one second roller has a (e.g. cylindrical) base body with a constant diameter, wherein the at least one second roller area with the second roller diameter is provided by an application material applied to the base body.

[0037] Preferably, the application material comprises, or is, an adhesive tape. The adhesive tape can be wrapped circumferentially around the base body in one or more layers to locally increase the diameter of the roller.

[0038] Preferably, the difference between the second roller diameter and the first roller diameter is a multiple (e.g., 2 to 7 times) of the coating thickness of an electrode coating (e.g., single-sided and / or calendered), particularly in the first web area of ​​the electrode web. 24-1475

[0039] Preferably, the at least one second roller comprises, or is, a segmented roller. The segmented roller can be produced, for example, by sliding and clamping rings of different diameters onto it.

[0040] Preferably, the at least one second roller comprises, or is, a (e.g., one-piece) roller with locally different diameters, which is produced, for example, by machining in the area with a lower diameter.

[0041] Preferably, the manufacturing system comprises, or is, a roll-to-roll system. A roll-to-roll system is a production system designed to continuously unwind flexible materials, such as films or tapes, from a take-up reel, guide them through various processing steps, and then wind them onto a take-up reel. Guide rollers (also known as "guide rollers") serve to precisely guide and support the flexible materials in the desired direction and to control their movement, ensuring consistent processing.

[0042] The roll-to-roll plant of the present disclosure comprises, or is, a calender plant for the manufacture of battery cells, such as lithium-ion cells.

[0043] Preferably, the electrode is intended for a drive energy storage system of a hybrid or electric vehicle, in particular for lithium-ion cells of the drive energy storage system. The drive energy storage system in a hybrid or electric vehicle is an energy storage system that stores electrical energy in the form of high-voltage direct current. This stored energy is used to drive at least one electric motor of the vehicle. Typically, these drive energy storage systems are composed of lithium-ion cells or modules configured in a battery pack. The drive energy storage system can also be referred to as a high-voltage storage system or battery.

[0044] The hybrid or electric vehicle can be, depending on the embodiment, a battery electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV). The term 24-1475

[0045] Vehicle includes cars, trucks, buses, motorhomes, motorcycles, etc., used for the transport of people, goods, etc. In particular, the term includes motor vehicles for passenger transport.

[0046] According to another independent aspect of the present disclosure, a manufacturing process for electrodes of battery cells, such as lithium-ion cells, is specified. The manufacturing process comprises:

[0047] Calendering of an electrode path by a first roller arrangement;

[0048] Heating the calendered electrode track by a heating arrangement; and

[0049] Processing the calendered electrode web before or after heating by at least a second roller of a second roller arrangement, wherein the at least one second roller comprises at least a first roller area with a first roller diameter and at least a second roller area with a second roller diameter, wherein the second roller diameter is larger than the first roller diameter, and wherein the at least one first roller area corresponds to a first web area of ​​the electrode web and the at least one second roller area corresponds to a second web area of ​​the electrode web, wherein the first web area and the second web area have different coatings and / or a different material properties.

[0050] Preferably, the processing of the calendered electrode web by the at least one second roller of the second roller arrangement takes place after the calendered electrode web has been heated by the heating arrangement. However, the present disclosure is not limited to this, and the processing of the electrode web by the second roller arrangement can alternatively also take place before heating or even before calendering.

[0051] The manufacturing process for battery cell electrodes can implement aspects of the battery cell electrode manufacturing system described in this document. 24-1475

[0052] Brief description of the drawings

[0053] Examples of the manifestation of the revelation are shown in the figures and are described in more detail below. They show:

[0054] Figure 1 schematically shows a manufacturing system for electrodes of battery cells according to embodiments of the present disclosure,

[0055] Figure 2 schematically shows a first roller arrangement and a heating device according to embodiments of the present disclosure,

[0056] Figures 3A and 3B schematically depict a second roller arrangement according to embodiments of the present disclosure, and

[0057] Figure 4 shows a flowchart of a manufacturing process for electrodes of battery cells according to embodiments of the present disclosure.

[0058] Implementations of the revelation

[0059] Unless otherwise noted, the same reference symbols are used for identical and equivalent elements in the following.

[0060] Figure 1 schematically shows a manufacturing system 100 for electrodes of battery cells, such as lithium-ion cells, according to embodiments of the present disclosure. Figure 2 schematically shows a first roller arrangement 110 and a heating device 120 of the manufacturing system 100. Figures 3A and 3B schematically show a second roller arrangement 130 of the manufacturing system 100.

[0061] In some embodiments, the manufacturing system 100 comprises, or is, a roll-to-roll system, in particular a calender system, for the manufacture of battery cells, such as lithium-ion cells. 24-1475

[0062] The manufacturing system 100 guides an electrode path EB in a predetermined path direction BR.

[0063] In some embodiments, the electrode EB comprises a substrate SUB or a support material, such as copper in the case of an anode or aluminum in the case of a cathode. On this substrate SUB, at least one layer AMI and at least one layer AM2 of an active material, such as graphite for the anode or lithium metal oxide for the cathode, are applied to both sides in a coating process (not shown). This double-sided coating ensures that the electrode provides a maximum active area for the electrochemical reactions, thus improving the performance and efficiency of the battery cells.

[0064] The manufacturing system 100 comprises a first roller assembly 110 configured to calender the electrode web EB. For this purpose, the first roller assembly 110 includes two first rollers 112A and 112B arranged on opposite sides of the electrode web EB to calender the electrode web EB between them.

[0065] The manufacturing system 100 further comprises a heating arrangement 120, which is configured to heat the electrode web EB after calendering by the first roller arrangement 110. Heating the electrode web EB after calendering selectively induces a springback, i.e., a rebound in the thickness of the electrode web EB (Figure 2). For example, overpressing UP may occur during calendering, and the heating of the electrode web EB can then be carried out such that the electrode web EB has a target thickness after heating. Triggering the springback immediately after calendering reduces camber and stress buildup.

[0066] Typically, the electrode path EB is a free electrode path during heating by the heating arrangement 120. A free electrode path after calendering refers to the section of the electrode path EB that is located immediately after calendering and is not supported by rollers or other machine parts. This part of the electrode path therefore "hangs" freely between the process steps.

[0067] In some embodiments, the heating arrangement 120 comprises at least one first heating device 122 A and at least one second heating device 122B, which are arranged on opposite sides of the electrode track EB. This allows, for example, the double-sided coated electrode track EB to be heated uniformly from both sides.

[0068] In some embodiments, the heating arrangement 120 comprises at least one infrared heating device. The at least one infrared heating device can, for example, be configured to heat the electrode path EB to a temperature of 80°C or more using an infrared wavelength in a range between 10⁻¹² and 5⁻¹²². However, the present disclosure is not limited to an infrared heating device, and, for example, at least one induction heating device and / or at least one gas heating device can also be provided, either additionally or alternatively.

[0069] The manufacturing system 100 further comprises a second roller arrangement 130, which is configured to selectively or locally lengthen the electrode web EB after heating to generate the springback. This is achieved by at least one second roller 132 with axially different diameters D1, D2. In particular, at least one first roller section with a first roller diameter D1 corresponds to a first web section B1 of the electrode web EB, and at least one second roller section with a larger second roller diameter D2 corresponds to a second web section B2 of the electrode web EB.

[0070] The first web section Bl and the second web section B2 have different coatings and / or different material properties, whereby different forces are exerted on the first web section Bl and the second web section B2 due to the different roller diameters D1, D2. This allows, in particular, compensation for a length difference between different 24-1475

[0071] This can occur in railway areas, e.g., in the direction of travel BR. Compensating for the length difference leads to a reduction in camber and a reduction in stress build-up.

[0072] In some embodiments, the first track region Bl of the electrode track EB corresponds to a region with an electrode coating, and the second track region B2 of the electrode track EB corresponds to a region without an electrode coating. In particular, the second track region B2 of the electrode track EB can correspond to a region with a current collector.

[0073] In some embodiments, the at least one second roller 132 has a (e.g., cylindrical) base body with a constant diameter (roller diameter D1), wherein the at least one second roller area with the second roller diameter D2 is provided by an application material 134 applied to the base body. The application material 134 can be, for example, an adhesive tape. The adhesive tape can be wrapped circumferentially around the base body in one or more layers to locally increase the diameter of the at least one second roller 132.

[0074] The difference between the second roller diameter D2 and the first roller diameter D1 can be a multiple (e.g. 2 to 7 times) of the coating thickness of an (e.g. single-sided and / or calendered) electrode coating of the electrode web EB, especially in the first web area Bl of the electrode web EB.

[0075] In some embodiments, the manufacturing system 100 further includes a web tension adjustment mechanism configured to adjust the web tension BZ of the electrode web EB at (e.g., before and / or after) the second roller assembly 130. The term "web tension" refers to the tension or tensile force exerted on the continuously moving electrode web EB as it passes through the manufacturing system 100. The targeted adjustment of the web tension BZ can further assist in compensating for length differences between the various web sections through the second roller assembly 130.

[0076] In some embodiments, the web tension adjustment mechanism is designed to adjust the web tension BZ of the electrode web EB at (e.g. in front of and / or behind) the second roller arrangement 130 in a range between 0.1 and 1.5 N / mm web width (Newtons per millimeter of web width), in particular in a range between 0.3 and 0.9 N / mm web width.

[0077] Figure 4 schematically shows a flowchart of a manufacturing process 400 for electrodes of battery cells according to embodiments of the present disclosure.

[0078] Manufacturing process 400 comprises, in block 410, calendering an electrode web by a first roller arrangement; in block 420, heating the calendered electrode web by a heating arrangement; and in block 430, processing the calendered electrode web after heating by at least one second roller of a second roller arrangement, wherein the at least one second roller comprises at least one first roller section with a first roller diameter and at least one second roller section with a second roller diameter, wherein the second roller diameter is larger than the first roller diameter, and wherein the at least one first roller section corresponds to a first web section of the electrode web and the at least one second roller section corresponds to a second web section of the electrode web, wherein the first web section and the second web section have different coatings and / or different material properties.

[0079] In the example shown in Figure 4, the calendered electrode web is processed by the at least one second roller of the second roller arrangement after the calendered electrode web has been heated by the heating arrangement. However, the present disclosure is not limited to this, and the processing of the electrode web by the second roller arrangement can alternatively also take place before heating or even before calendering. According to the invention, a heating process of the electrode web is carried out after calendering to selectively generate a springback, i.e., an increase in the thickness of the electrode web. Subsequently, a further process step is carried out in which specific areas of the electrode web are elongated by a roller with a locally increased diameter. For example, force can be applied to an area with an uncoated conductive foil, causing this area to undergo plastic elongation.This allows, in particular, the compensation of length differences between coated and uncoated areas. The combination of both measures, i.e., heating and local elongation, leads to a reduction in camber and a reduction in voltage build-up. This results in improved electrode quality as well as increased reliability and a longer lifespan for the battery cells.

[0080] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are truly only examples and are not to be understood in any way as limiting, for example, the scope of protection, the possible applications, or the configuration of the invention.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

Claims

24-1475 Patent claims 1. Manufacturing system (100) for battery cell electrodes, comprising: a first roller arrangement (110) configured to calender an electrode web (EB); a heating arrangement (120) configured to heat the electrode web (EB) after calendering;and a second roller arrangement (130) with at least one second roller (132), wherein the at least one second roller (132) comprises at least one first roller section with a first roller diameter (D1) and at least one second roller section with a second roller diameter (D2), wherein the second roller diameter (D2) is larger than the first roller diameter (D1), and wherein the at least one first roller section corresponds to a first web section (Bl) of the electrode web (EB) and the at least one second roller section corresponds to a second web section (B2) of the electrode web (EB), wherein the first web section (Bl) and the second web section (B2) have different coatings and / or different material properties.

2. Manufacturing system (100) according to claim 1, further comprising a web tension adjustment mechanism configured to adjust a web tension (BZ) of the electrode web (EB) on the second roller arrangement (130), in particular wherein the web tension adjustment mechanism is configured to adjust the web tension (BZ) of the electrode web (EB) in a range between 0.1 and 1.5 N / mm web width.

3. Manufacturing system (100) according to claim 1 or 2, wherein the heating arrangement (120) comprises: at least one first heating device (122A) and at least one second heating device (122B) arranged on opposite sides of the electrode track (EB); and / or at least one infrared heating device; and / or at least one induction heating device; and / or 24-1475 at least one gas heating appliance.

4. Manufacturing system (100) according to any one of claims 1 to 3, wherein the heating arrangement (120) is configured to: heat a surface of the electrode path (EB) to a temperature of 80°C or more; and / or heat the electrode path (EB) for a heating duration of 0.5s or more; and / or heat the electrode path (EB) with an infrared wavelength in a range between 1 and 5pm.

5. Manufacturing system (100) according to one of claims 1 to 4, wherein the first web area (Bl) of the electrode web (EB) corresponds to an area with an electrode coating .

6. Manufacturing system (100) according to any one of claims 1 to 5, wherein: the second track region (B2) of the electrode track (EB) corresponds to a region without electrode coating; and / or the second track region (B2) of the electrode track (EB) corresponds to a region with a current collector.

7. Manufacturing system (100) according to any one of claims 1 to 6, wherein: the at least one second roller (132) has a base body with a constant diameter (D1), and wherein the at least one second roller area with the second roller diameter (D2) is provided by an application material (134) applied to the base body, in particular wherein the application material (134) comprises or is an adhesive tape; or the at least one second roller comprises or is a segmented roller.

8. Manufacturing system (100) according to one of claims 1 to 7, wherein a difference between the second roller diameter (D2) and the first roller diameter (D1) 24-1475 is a multiple of a coating thickness of an electrode coating (AMI, AM2) of the electrode path (EB), especially in the first path region (Bl) of the electrode path (EB).

9. Manufacturing system (100) according to any one of claims 1 to 8, wherein the manufacturing system (100) comprises or is a roll-to-roll system.

10. Manufacturing process (400) for electrodes of battery cells, comprising: Calendering (410) of an electrode web (EB) by a first roller arrangement (HO); Heating (420) of the calendered electrode path (EB) by a heating arrangement (120); and Processing (430) the calendered electrode web (EB) before or after heating by at least one second roller (132) of a second roller arrangement, wherein the at least one second roller (132) comprises at least one first roller section with a first roller diameter (D1) and at least one second roller section with a second roller diameter (D2), wherein the second roller diameter (D2) is larger than the first roller diameter (D1), and wherein the at least one first roller section corresponds to a first web section (Bl) of the electrode web (EB) and the at least one second roller section corresponds to a second web section (B2) of the electrode web (EB), wherein the first web section (Bl) and the second web section (B2) have different coatings and / or different material properties.

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